1. Field of the Invention
The present invention relates to a method and device for use in the treatment of wastewater from home wastewater streams or other individual small sources that convert nitrates to nitrogen gas, thus reducing the amount of nitrates introduced into the aquifer to avoid eutrophication and the introduction of levels of nitrate in drinking water detrimental to human health. More specifically, the invention relates to the use of bacteria in tablet form and a dispenser for such tablets for denitrification in a home sewage treatment system.
2. The Process with Which This Method and Device Are Used
The treatment of wastewater from homes in which this method and device are used is disclosed in my co-pending application, Ser. No. 07/532,790 filed Jun. 4, 1990 now abandoned in favor of continuation application Ser. No. 07/809,101 filed Dec. 11, 1991 for SYSTEM FOR THE ON-SITE REMOVAL OF NITRATES FROM WASTEWATER (hereinafter "the said application"), which is incorporated by reference herein. As related therein, while nitrogen is of primary importance in the renovation of sewage, excessive concentrations of nitrogen compounds in groundwater are a public health hazard and also contribute to the eutrophication of surface water The presence of nitrite (NO.sub.2 --) and, indirectly nitrate (NO.sub.3 --) in drinking water may lead to methemoglobinemia which can impair oxygen transport in the blood, particularly in infants where gastrointestinal upsets can encourage reduction of nitrite to nitrate. The hazards of these materials and their precursors, the nitrosamines, in the soil and aquifer are explained in the said application.
In the said application, the invention disclosed is based upon the novel concept of employing the temperature of the earth and, more specifically, the ground temperature adjacent to the discharge of home or other small wastewater streams to provide the necessary activation temperature for known denitrifying bacteria in a system receiving the effluent from home or commercial wastewater streams.
It is necessary to introduce bacteria on a periodic, especially daily, basis in order to provide excess bacteria, even double or triple the amount normally or hypothetically present in a commercial or municipal reactor or filter. The purpose of providing excess bacteria in this way is to make it possible to accommodate fluctuation in the ammonia content of the wastewater being treated. The ammonia content of such wastewater streams varies geographically and seasonally and, while averaging about 40 mg/l around the country, may range as high as 60 mg/l or more. The bacteria is supplied in tablet form.